Det Act Insp Peachey believes the attacker is a 20-year-old man known to the 16-year-old victim, but nobody is in police custody at this time.

"It would appear that nothing was stolen from the address, but a number of threats and the reason for the assault is still being investigated," he said.

Det Act Insp Peachey said police attended the scene in a matter of minutes supported by the dog squad and other specialised units to declare a crime scene.

"Forensics have attended the scene and there are a number of leads to go off as a number of items were left," he said.

Det Act Insp Peachey said it could have been a lot worse.

He said the three other male offenders were described as Aboriginal in appearance, small-to-thin build and between the ages of 13 and 16 years old.

The teenagers were last seen in dark clothing exiting the premises and Det Act Insp Peachey asked for assistance from anybody who saw people matching this description to resolve the investigation quickly.